When you insert an image into a WordPress post or page, you’ll notice that you have the option to choose the image size (thumbnail, medium, large, any custom sizes your theme utilizes), as well as where the image links (media file, attachment page, custom, none). What if you want to change those defaults? For instance, if you want the inserted images to default to large or the link to default to none.
Enter the magical hidden WordPress admin options page. You can access this page by going to: yoursiteurl.com/wp-admin/options.php
If you scan those values, you’ll notice there are listed fields for:
You can modify those to adjust default behavior. For the link type to be none, leave the image_default_link_type empty. You can also put file, to link to the media file, or post, to link to the attachment page.
For image_default_size, you can put thumbnail, medium, large or any custom size name your theme utilizes.
A couple notes:
Don’t get too crazy with adjusting other options you see on this options panel. Some values within it have to be a certain way for various plugins & the rest of your site to continue working correctly. You are messing with database options by adjusting these values so, as always, it is recommended to play it safe and make a backup before touching these items.
Nothing changed here will retroactively work on images. What I mean by that is if you select that you want the images to link to nothing vs. the media file, it will just default to that value moving forward. It will not go and change any image linking to a media file.